Stem cell transplants help extend survival time for blood cancer patients, and are delivered in one of two ways: Autologous transplants, taken from stores of a patient’s own stem cells, or allogeneic transplants, which uses stem cells from a donor.

Most people’s biological age, the age of their cells, is different from their age in years. Many cancer treatments carry side effects, such as fatigue, nausea and hair loss, and researchers were not surprised to find accelerated aging.

“Many oncologists would not be surprised by the finding that stem cell transplant accelerates aspects of aging,” Dr. Norman Sharpless, director of the Lineberger Comprehensive Cancer Center at the University of North Carolina, said in a press release. “We know that years after a curative transplant, stem cell transplant survivors are at increased risk for blood problems that can occur with aging, such as reduced immunity, increased risk for bone marrow failure, and increased risk of blood cancers. What is important about this work, however, is that it allows us to quantify the effect of stem cell transplant on molecular age.”

For the study, the researchers analyzed blood samples from 63 cancer patients, 26 of whom underwent autologous transplants and 37 of who received allogeneic transplants. Most of the autologous transplant recipients had myeloma, and some also had lymphoma, while most of the allogeneic transplant recipients had leukemia. Five of the allogneneic recipients had also previous received autologous transplants.

Researchers found higher expression of mRNA coding for the p16 protein, which is expected to increase exponentially as people age chonologically, in both groups of cancer patients. In those who received an autologous transplant, however, patients had three times the p16 expression they had before transplant — a significant increase.

“We know that transplant is life-prolonging, and in many cases, it’s life-saving, for many patients with blood cancers and other disorders,” said Dr. William Wood, an associate professor in the UNC School of Medicine‘s Division of Hematology and Oncology and lead author of the study. “At the same time, we’re increasingly recognizing that survivors of transplant are at risk for long-term health problems, and so there is interest in determining what markers may exist to help predict risk for long-term health problems, or even in helping choose which patients are best candidates for transplantation.”